1. Field of the Invention
The present invention relates to a vehicle regeneration cooperative braking system which includes
a regenerative braking device connected to an axle of one of left and right front wheels and left and right rear wheels and adapted to produce a regenerative braking force by electrical regeneration at the time of braking,
a brake hydraulic pressure generating source for generating a brake hydraulic pressure,
regeneration side left and right wheel brakes of a hydraulic type which are mounted, respectively, on either of the left and right front wheels and either of the left and right rear wheels,
non-generation side left and right wheel brakes of a hydraulic type which are mounted, respectively, on the other of the left and right front wheels and either of the left and right rear wheels,
a first hydraulic system brake line including a first common brake line portion which communicates with the brake hydraulic pressure generating source and a pair of first separate brake line portions which branch off the first common brake line portion so as to be connected individually to the regeneration side left wheel brake and the non-regeneration side right wheel brake,
a second hydraulic system brake line including a second common brake line portion which communicates with the brake hydraulic pressure generating source and a pair of second separate brake line portions which branch off the second common brake line portion so as to be connected individually to the regeneration side right wheel brake and the non-regeneration side left wheel brake,
a pair of normally closed electromagnetic isolation control valves which are provided in positions along the lengths of the first common brake line portion and the second common brake line portion, respectively,
normally open electromagnetic pressure supply valves which are individually provided in positions along the lengths of the pair of first separate brake line portions and the pair of second separate brake line portions, respectively,
normally closed electromagnetic pressure relief valves which are individually interposed between the respective wheel brakes and a reservoir, and
a controller for controlling operations of the regenerative braking device, the electromagnetic isolation control valves, the normally open electromagnetic pressure supply valves and the normally closed electromagnetic pressure relief valves when a regeneration cooperative braking is implemented in which part of a required braking force is obtained by the regenerative braking device.
2. Description of Related Art
A regeneration cooperative braking system is known in Japanese Patent Unexamined Publication JP-A-2002-87234 which includes
a first hydraulic system brake line which connects a braking hydraulic pressure generating source with a left front wheel brake and a right rear wheel brake,
a second hydraulic system brake line which connects the braking hydraulic pressure generating source with a right front wheel brake and a left rear brake line,
a normally open electromagnetic valve which is provided in a position along the length of the first hydraulic system brake line for common use for the left front wheel brake and the right rear wheel brake,
a normally open electromagnetic valve which is provided in a position along the length of the second hydraulic system brake line for common use for the right front wheel brake and the left rear wheel brake,
normally open electromagnetic pressure supply valves which are provided in positions along the lengths of the first and second hydraulic system brake lines, respectively, in such a manner as to be individually associated with the respective wheel brakes, and
normally closed electromagnetic pressure relief valves which are interposed individually between the respective wheel brakes and a reservoir,
wherein braking by the wheel brakes and regenerative braking by a regenerative braking device which produces a regenerative braking force by virtue of electrical regeneration are made to cooperate with each other.
In regeneration cooperative braking systems like the one described above, although the hydraulic pressures of the respective wheel brakes can be controlled by combining opening and closing controls of the electromagnetic isolation control valves, as this occurs, the number of operating electromagnetic valves which are caused to operate to open and close through an electric current is desirably made as small as possible with a view to realizing a reduction in operation noise, an increase in durability and a reduction in consumed power.